Early life thermal stress: Impacts on future temperature preference in weaned pigs (3 to 15 kg)

Authors: ROBBINS, LINDSEY - Purdue University; GREEN-MILLER, ANGELA - University Of Illinois; Johnson, Jay; GASKILL, BRIANNA - Purdue University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2020
Publication Date: 12/1/2020
Citation: Robbins, L., Green-Miller, A.R., Johnson, J.S., Gaskill, B.N. 2020. Early life thermal stress: Impacts on future temperature preference in weaned pigs (3 to 15 kg). Journal of Animal Science. 98(12). https://doi.org/10.1093/jas/skaa327.
DOI: https://doi.org/10.1093/jas/skaa327

Interpretive Summary: Early life experiences can influence the future behavior, stress response, and welfare of pigs. Specifically, exposure to both heat stress and cold stress in early life can alter a pig’s body temperature response and behavioral response to thermal stress later in life. As a result, this may influence how producers should manage their pigs depending on early life experiences. Therefore, the study objective was to investigate whether early life heat stress or early life cold stress would influence the temperature preference of pigs later in life. We hypothesized that pigs exposed to early life heat stress would prefer a cooler temperature and that early life cold stressed pigs would prefer warmer temperatures relative to controls. It was determined that pigs exposed to early life cold stress preferred warmer temperatures when compared to control pigs. However, no thermal preference differences were detected between early life heat stressed pigs and control pigs. These results have implications towards the future thermal management of pigs that may be exposed to cooler temperatures during early life development.

Technical Abstract: Thermal stress can result in productivity losses, morbidity, and mortality if proper management practices are not employed. A basic understanding of the relationship between animals and the thermal environment is crucial to assess the environment’s impact on livestock performance. Therefore, the study objective was to evaluate whether different early life thermal stressors (ELTS) altered the temperature preference of piglets later in life. Twelve sows and their litters were randomly exposed to one of three ELTS treatments from 7 to 9 d of age: early life heat stress (ELHS; cycling 32 to 38ºC; n=4), early life cold stress (ELCS; 25.4±1.1ºC without heating lamp; n=4), or early life thermoneutral (ELTN; 25.4±1.1ºC with a heating lamp; n=4) conditions. From 10 to 20 d (weaning) all pigs were exposed to ELTN conditions. At weaning, piglets were randomly assigned to groups of 4 of the same sex and ELTS treatment. Temperature preference, where piglets freely choose a temperature, was assessed in 21 groups (n=7 groups per ELTS treatment) using one of three thermal gradient apparatuses (22 to 40°C). Testing began at 26±1.3 d of age to give piglets time to acclimate to solid food after weaning and one group per ELTS treatment were tested simultaneously in each apparatus. Piglets were given 24 h to acclimate followed by a 24 h testing period. Behavior (active and inactive), posture (upright, sternal and lateral lying), and location were documented every 20 min using instantaneous scan samples. Preferred feeding temperature was determined by the latency to empty a feeder in each location. Data were analyzed using PROC MIXED in SAS 9.4. A quadratic regression model was used to calculate the peak temperature preference of piglets based on the temperature piglets spent most of their time. The preference range was calculated using peak temperature preference ±SE for each ELTS treatment group. Early life thermal stress altered where piglets spent most of their time within the thermal gradient (P =0.03) with ELTN piglets preferring cooler temperatures (peak preference of 23.8°C) compared to their ELCS exposed counterparts (peak preference of 26.0°C; P <0.01). However, ELHS exposed piglets (peak preference of 25.6°C) did not differ in their temperature preference compared to ELTN or ELCS exposed counterparts (P >0.05). In summary, ELCS exposure altered piglet temperature preference later in life indicating ELTS can alter temperature preference in pigs.